This invention relates to the installation of masonry anchors and more particularly to the installation of screw threaded masonry anchors which form threads in masonry structures.
Prior art devices and methods have had two distinct problems involving the rate of axial penetration of such anchors. First, a workman installing a threaded masonry anchor in masonry which is either hard or which has no predrilled hole may have difficulty exerting enough axial force to insure a steady rate of axial penetration. Stripping of the threads formed in the structure occurs if the anchor does not penetrate continuously. Secondly, in softer masonry, a workman can inadvertently exert an excessive amount of axial force causing the anchor to penetrate too quickly. These problems are particularly troublesome when the properties of a particular structure are variable and not apparent. It may be difficult for a workman to determine the proper amount of axial force to insure continuous penetration and at the same time hold back to prevent stripping due to excess axial force. Prior art devices and methods generally rely on threads formed in the structure to provide resistance to axial forces. This reliance makes stripping of formed threads a major problem.
It is primary object of the present invention to provide a device, method and system for controlling the rate of axial penetration of a threaded masonry anchor to prevent stripping of threads formed in a masonry structure.
Another object of the invention is to provide a reusable device for controlling the rate of axial penetration of a threaded masonry anchor.
These objects are achieved by placing a plate between a threaded masonry anchor and a masonry structure. An opening in the plate allows engagement of the anchor with the plate. Rotation of the plate is prevented as axial and rotational forces are applied to the anchor. As the anchor passes through the plate, the plate may be used to resist axial forces on the anchor in either axial direction. By using the plate as an intermediate medium having a known strength, a workman can control the rate of axial penetration of the anchor and preclude stripping of threads formed in the masonry structure.